The present invention relates to electrical conductors and, more specifically, to electrical conductors for fluid filled power units.
Power units are used in many types of mobile machinery. Hydraulic machines such as hydraulic pumps and hydraulic motors are typical examples of power units. Electrical machines such as electrical motors, generators, and alternators are also commonly used power units. Power units such as electrical motors are commonly used to power mobile machinery and are oftentimes flooded or cooled with hydraulic fluid or other fluids. In some instances, these electrical motors are completely submerged in the fluid for improved cooling and thereby allow more power to be produced by a motor of a specific size while preventing damage to the motor from such increased power levels. Because of this, the components of electrical motors are enclosed in a leakproof housing. As such, it is necessary to provide a means for connecting the electrical wires that provide power to the motor through the housing while sealing against leakage of the hydraulic or other fluid through this connection. Further, as the housing typically is made of metal or other conductive materials, it is necessary to insulate the electrical connections from the housing. The same need applies not only to electrical motors but to all electrical machines used in mobile machinery, as well as, to hydraulic machines such as hydraulic pumps and hydraulic motors.
U.S. Pat. No. 3,850,501 to Butterfield et al. discloses a feedthrough electrical terminal for use in a liquid cooled shaft. Butterfield et al. accomplishes a leakproof and insulated connection through the use of non-metallic bushings and washers compressed by a threaded female terminal member. The disadvantage Butterfield et al. is that such a design requires numerous components, many of which are non-standard and must be custom machined.
U.S. Pat. No. 4,822,473 to Arnesen and U.S. Pat. No. 6,657,336 to Morikaku et al. both disclose electrical connectors that are comprised of standard pieces of hardware. Specifically, both of these patents disclose the use of standard terminal bolts as conductors. Morikaku et al. also discloses the use of insulating elements to protect the terminal bolt conductor from the metallic housing. The disadvantage of both of these designs is that they are both susceptible to leakage. As such, Arnesen and Morikaku et al. would not be useful in the specific application of a fluid filled power unit.
U.S. Pat. No. 4,614,397 to Flanigan discloses a terminal plate assembly that teaches the use of a terminal bolt as a conductor. Further, Flanigan teaches the use of terminal blocks that serve to both insulate and seal the bolt. The disadvantage of the Flanigan assembly is that it requires the use of intricately machined terminal blocks to accomplish a leakproof seal.
It is therefore a principal object of this invention to provide an electrical conductor for passing through the housing of a fluid filled power unit that is insulated from the housing and utilizes a minimal number of parts.
A further object of this invention is to provide sealing means to prevent leakage from the fluid filled power unit through the electrical conductor.
These and other objects will be apparent to those skilled in the art.